package base.study;

import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;

public class YMap{
	
	public static void main(String[] args) {
		yHashMapNullKey();
	}
	
	public static void yHashMapNullKey(){
		HashMap<String, String> map0=new HashMap<String, String>(13);
		Map<String, String> map=new HashMap<String, String>(13);
		map.put("yaoming", "yaoming");
		map.put(null, "yaoming2");
		System.out.println(map.get(null));
		System.out.println(map0);
	}
	
	public static void yTreeMap(){
		TreeMap<String, String> map=new TreeMap<String, String>();
		System.out.println(map);
	}
}
